An environmentally friendly approach to the green synthesis of azo dyes with aryltriazenes via ionic liquid promoted C-N bonds formation.

An efficient and green approach for the synthesis of azo dyes has been developed via the Brønsted acidic ionic liquid (IL) promoted diazo coupling reaction of naphthols with aryltriazenes. The reaction was carried out with the aryltriazenes as diazotizing agents, the Brønsted acidic ionic liquids as the promoter, and water as the green solvent at room temperature under air and metal-free conditions. Notably, the attractive advantages of the process include mild conditions with excellent yields, simple product isolation process, large-scale experiment, late-stage modification of pharmaceutical and recyclability of the promoter. In addition, the UV-vis spectral characteristics of the azo-dyes were investigated in DMSO. [ABSTRACT FROM AUTHOR]